In the following description, it will be described that the invention is a capsule for use in the preparation of liquid foods, particularly beverages. However, it should remain clear that the invention also encompasses other types of flowable edible compositions, such as semi-liquid food like soups, gels, creams, soft ice cream and so on.
Generally, beverage preparation machines are well known in the food industry and consumer goods domain. Such machines allow a consumer to prepare on command a single serving of a beverage such as brewed coffee, espresso coffee, tea, hot chocolate drink, or the like.
Most beverage preparation machines for in-home use operate according to a system in which beverage ingredients are provided as individually-packaged, single-serving portions. Such portions can be soft pods, pads, or sachets, but increasingly more systems use semi-rigid or rigid portions such as rigid pods or capsules. In the following, it should be understood that the beverage machine in question is a beverage preparation machine working with a rigid or semi-rigid capsule.
In many instances, the capsules for use in beverage preparation machines are sealed. Such sealed capsules are advantageous in that they protect the ingredient contained therein from the surrounding atmosphere, improving the shelf life of the capsule. Typically, such closed capsules are made from a gas and/or moisture impermeable material, and feature a rigid or semi-rigid body having one of its walls made from a flexible membrane.
The beverage is prepared by inserting the capsule into a beverage machine, which preferably comprises a receptacle for accommodating said capsule and a fluid injection system for injecting a fluid (preferably water) under pressure into said capsule. In most applications, the water injected into the capsule under pressure is heated, generally to a temperature above 70° C. However, in some particular instances it may be advantageous to inject ambient or chilled water instead. The pressure inside the capsule chamber during extraction and/or dissolution of the capsule contents is typically about 1 to about 8 bar for dissolution products and about 2 to about 12 bar for extraction of roast and ground coffee.
The present invention could also encompass the so-called “brewing” process of beverage preparation—particularly for tea and coffee. Brewing involves the infusion over time of the ingredient in a fluid, most commonly hot water, whereas extraction or dissolution preparations produce a beverage within a few seconds.
For purposes of clarity, however, in this document the term “brewing” of an ingredient by a fluid is understood to encompass extraction of a powdered edible material (e.g. roast and ground powdered coffee), dissolution of edible soluble material (e.g. soluble tea, coffee, milk, or cocoa), or the infusion of an edible material in an infusion fluid under very low or atmospheric pressure, for a longer time than that required for extraction or dissolution (e.g. tea leaves in hot water).
The principle of extracting and/or dissolving the contents of a closed capsule under pressure is known and consists typically of confining the capsule in a receptacle of a machine, injecting a quantity of pressurized water into the capsule to extract or dissolve the substance, and then dispensing the resulting beverage from the capsule.
The injection is generally performed by piercing a face of the capsule with a piercing injection element, such as a fluid injection needle incorporated into the machine. Capsules applying this principle have already been described, for example in applicant's European patent no° EP 1 472 156 B1, and in EP 1 784 344 B1.
In addition, machines applying this principle have already been described for example in patents CH 605 293 and EP 242 556. According to these documents, the machine comprises a receptacle for the capsule, and a perforation and injection element made in the form of a hollow needle comprising in its distal region one or more liquid injection orifices. The needle has a dual function in that it simultaneously opens the top portion of the capsule while providing an inlet channel into the capsule for the injection of the water.
The machine comprises a supply of the fluid (usually water) that is used to prepare the beverage from the ingredient(s) contained in the capsule. The machine further comprises a heating unit such as a boiler or a heat exchanger, which heats the water used therein to working temperatures (usually between 80° and 90° C.). Finally, the machine comprises a pump for circulating the water from the tank to the capsule, optionally though the heating unit. The circulation of the water within the machine may be directed via a selecting valve means, such as for instance a peristaltic valve of the type described in applicant's European patent application EP 2162653 A1.
Such systems are particularly well-adapted to the preparation of coffee. One configuration for achieving this which is particularly advantageous is to provide a capsule containing roast and ground coffee powder, which is extracted with hot water injected therein.
Capsules have been developed for such an application, which are described and claimed in applicant's European patent EP 1 784 344 B1, or in European patent application EP 2 062 831.
In short, such capsules typically comprise:                a hollow body and an injection wall which are impermeable to liquids and to air, the wall being attached to the body and adapted to be punctured by e.g. an injection needle of the machine;        a chamber containing a bed of roast and ground coffee to be extracted;        an aluminium membrane disposed at the bottom end of the chamber for retaining the internal pressure therein, the membrane being associated with piercing means which create drainage holes in the aluminium membrane when the internal pressure inside the chamber reaches a certain pre-determined value; and        optionally, a deflection means configured to break up the jet of fluid, thereby reducing the speed of the jet of fluid injected into the capsule and evenly distributing the fluid across the bed of substance at a reduced speed.        
During extraction, the beverage capsule is pierced by the fluid injection needle of the beverage preparation machine. The liquid is injected in the capsule compartment and the pressure within the capsule increases, facilitating the extraction of the beverage from the ingredients contained within the capsule.
Once prepared within the capsule, the product is dispensed to the consumer's cup or similar receptacle through a dispensing channel or dispensing opening.
Many flowable products prepared with a capsule as described above are available, many of which are supposed to contain a foamed portion. Foam gives a creamy and light mouthfeel, and boosts the organoleptic experience of the consumer, as it creates an interface between the liquid and the gaseous phases of the product. Foam is therefore an important component for some products.
A foam phase is generally created by the tight mixing of a gaseous phase into a liquid phase. Concerning flowable foods and beverages, foam is generally created by mixing air with the liquid product. The finer the bubbles, the stronger and creamier the foam. Some ingredients can also be added to the composition to enhance and/or stabilize the foam. For instance proteins are known to provide a better foaming quality. In all cases though, the minimal requirement for the creation of foam is the presence of air mixed in the liquid phase.
Unfortunately though, it was found that many systems using capsules for the easy preparation of beverages, provide poor foaming capabilities, and/or involve expensive structural design to provide such foaming capabilities.
Some known capsules comprise air vents located within the capsule compartment, or at an entry point of the capsule compartment such as described in European patent publication EP 2058243 B1. Such capsules require piercing the capsule wall with an air vent, which produces risks of leakage.
Some other capsules comprise foaming means inserted within the capsule compartment, which require a specific and somehow complex flowpath to ensure that said foaming means can operate. However, such internal devices do not allow air, or generally a gas, to be mixed with the liquid product to produce a foam.
There is therefore a need for a container, for instance a capsule, for producing flowable food or beverages, that comprises means able to produce foam, without the disadvantages of the known solutions.